Health experts say Kiwis travelling to Indonesia should pay close attention to the source of any alcohol they drink, and avoid jugs of pre-made liquor.
Dr Leo Schep, a toxicologist at the National Poisons Centre in Dunedin, said very little pure methanol was needed to have deadly results.
"All you need is half a millilitre per kilogram of body weight, so if you're 80kg, you need 40ml of pure methanol to have a potentially lethal dose."
Dr Schep said physical symptoms were similar to drunkenness and could appear vague at first.
If untreated, the poisoning could lead to rapid breathing, blindness, a coma and seizures which could lead to brain damage.
About one-third of serious poisoning victims suffered irreversible visual impairment, but victims' lives could be saved if they received medical treatment quickly.
The antidote was ethanol, or alcohol, which acted as a blocking agent.
"If they are out drinking alcohol, they are administering the antidote at the same time. But the problem is the alcohol is removed quicker from the body than the methanol."
Christchurch Hospital emergency department doctor Paul Gee published a paper last year on methanol poisoning after treating a 19-year-old North American backpacker who was left partially blind.
Dr Gee said the woman had eight to 10 cocktails in Indonesia the night before she flew to Christchurch.
About 30 hours after having the drinks, she began to experience symptoms.
"The first thing she felt was panic, distress. Then her vision was getting darker and darker, like she was in a twilight room ... Within a few hours we'd organised dialysis to try to get rid of the methanol ... but even then, she lost pretty much most of her vision."
Dr Gee said bars in tourist areas of Indonesia put out free drinks in an effort to attract patrons.
Those drinks often contained home-brewed spirits, which were poorly made and dangerous.